NICHOLSON SKIDDAW GRAPTOLITES. 145 



Graptolites Sagittarius, Linn. (?) 



tenuis, Port. (?) 



Nilssoni, Barr. (?) 



Phyllograpsus angustifoKus, Hall. 



typus, Hall. 



Tetragrapsus hryonoides, Hall {^ Didymograpsus caduceus, Salt.). 



crucifcr, Hall. 



Headi, Hall. 



quadribrachiatus, Hall {—T. crucialis, Salt.). 



Pleurograpsus (?) vagans, Nich. 



EXPLANATION OF PLATES V. & VI. 



{Illustrative of the Graptolites of the Skiddaw series.) 

 The figures are drawn from nature, unless it is otherwise stated. 



Plate V. 



Figs. 1 & 2. Dichograpsus octobrachiatus, Hall: — (1) A specimen showing 

 the central disk, and one of the celluliferous stipes in full : 

 after Hall; natural size. (2) A small and imperfect spe- 

 cimen of tliis species (?) from Mirehouse, near Skiddaw: na- 

 tural size. 

 3-5. Dichograpsus reticulatus, Nich. : — (3) A fragment from Barff, 

 natural size. (4) A specimen from the collection of Professor 

 Harkness, natural size. (5) Portion of fig. 4 magnified five 

 diameters. 

 6 & 7. JDendrograpsus Hallianus (?) Prout : — (6) A specimen from EUer- 

 gill, natural size. (7) A portion of the same, magnified five 

 diameters. 

 8-10. Didymograpsus geminus, His.: — (8) A specimen having the 

 branches not very divergent, natural size. (9) The same, mag- 

 nified two diameters. (10) Another specimen with a rounder 

 base, natural size. 

 11-13. Biplograpsus teretiusculus, His.: — (11) A specimen from Eller- 

 gill, natural size. (12) A portion of the same, magnified two 

 diameters, (13) A portion of another specimen, magnified two 

 diameters. 



14 & 15. Biplograpsus pristiniformis, Hall: — (14) Base of a stipe, magni- 

 fied three diameters. (15) A portion of a specimen apparently 

 belonging to this species, in which the cellules are furnished 

 with small spines at their apices : magnified three diameters. 



Fig. 16. Phyllograpsus typus, Hall. From Barff", natural size. 



Plate VI. 



Figs. 1-3. Dichograpsus omiltiplex, Nich. : — (1) A specimen, from the collec- 

 tion of Professor Harkness, showing the funicle (a) and the 

 dichotomizing stipes : natural size. (2) Fragment of the same, 

 enlarged to show the form and relations of the cellules. (3) 

 A single dichotomizing stipe, from the collection of Professor 

 Harkness : natural size. These figures have been copied from 

 sketches by the author. 

 4 & 5, Pleurograpsus ? vagans, Nich. : — (4) A specimen from Crum- 

 mock, natural size. (5) A portion of the same, magnified two 

 diameters. 



